1. Field of the Invention
This invention relates generally to interconnecting computers and peripheral devices and, more particularly, to a system and method for automatically changing a transmit/receive configuration a computer, peripheral device, or both to establish a link between multiple devices.
2. Description of Related Art
Over the past several years, personal computers and peripheral devices have become commonplace. The vast majority of business offices have personal computers in them, and the use of personal computers in homes is growing rapidly as well. Most offices, and many homes, have more than one personal computer and it is often desirable to interconnect these computers or to utilize one printer or other peripheral device with more than one personal computer.
It is well known that Local Area Networks (LANs) can be established in these locations to network computers and to allow more than one computer to access such peripheral devices. In general, LANs connect a community of devices such as personal computers, servers, microcomputers, workstations, and printers in a localized area. One objective of some LANs is to allow multiple users to share peripherals, including printers and shared storage. Another objective is the sharing of files and applications between computers.
Today, local area networking is a shared access technology. This means that the devices attached to the LAN share a single communications medium, usually a co-axial twisted pair cable, or fiber-optic cable, for example. A widely used LAN technology in use today is Ethernet. The Institute of Electrical and Electronics Engineers (IEEE) defines and describes the Ethernet standard in a specification commonly known as IEEE 802.3, which is incorporated herein by reference.
In general, an Ethernet connection typically includes two pairs of unshielded twisted pair wires, a total of four wires. One pair of wires is called the transmit pair (Tx+ and Txxe2x88x92) and the other pair is called the receive pair (Rx+ and Rxxe2x88x92). Because Ethernet end stations and Ethernet hubs frequently use opposite pairs to transmit and receive, an Ethernet end station and an Ethernet hub may be interconnected with a standard xe2x80x9cstraight-throughxe2x80x9d Ethernet cable to align respective transmit and receive locations. A straight-through Ethernet cable connects transmit pins at one end of the cable with transmit pins at the other end of the cable, as well as connecting receive pins at one end of the cable with receive pins at the other end of the cable.
Conventionally, however, a xe2x80x9ccrossoverxe2x80x9d cable must be used to directly interconnect an Ethernet end station and another Ethernet end station, or to directly connect an Ethernet hub to another Ethernet hub so that the various transmit and receive signals are sent to the appropriate locations. A crossover cable interconnects the pins used as the transmit pair at one end of the cable with the pins used as the receive pair at the other end of the cable and vice versa.
Hence, in some Ethernet connections, a straight-through cable is required, while in other Ethernet connections, a crossover cable is required. Unfortunately, particularly for lay users, determining whether to use a straight-through cable or a crossover cable may be confusing, which could lead to a failure to install the correct cable. Using the wrong cable will, conventionally, result in an unsuccessful Ethernet connection.
Consequently, a need exists for a system and method by which transmit and receive connector components of a device may be automatically reconfigured to achieve a link with another device. An additional need exists to provide a system and method for reliably configuring an Ethernet connection regardless of the type of Ethernet appliance (hub or end station) or the type of cable (straight-through or crossover) employed.
The present invention relates to a system and method by which device transmit and receive connector components are automatically configured to establish a link. In general, the present invention provides a multiplexer associated with each of a plurality of leads, or outputs, and having either a software or a hardware entity monitor a link indicator and automatically switch the multiplexers as needed to establish or maintain a link. Thus, the multiplexers switch the connector configuration until a link is established.
In one embodiment, the invention comprises a first Ethernet device for generating data to be transmitted across a transmission network system. The first Ethernet device includes a first physical layer for preparing the data for transmission. A second Ethernet device is also coupled to the transmission network system for receiving data from the transmission network and includes a second physical layer for receiving the data. An auto-configuration device is coupled to the first physical layer for detecting the existence of an Ethernet link and switching the line configuration to another configuration until detecting an Ethernet link.
The auto-configuration device may comprise a multiplexer circuit for switching the line configuration to a different line configuration until receiving a xe2x80x9clink establishedxe2x80x9d signal. An auto-configuration controller monitors the status of the link, which may comprise an Ethernet link, and controls the multiplexers according to the status of the link.
One embodiment of the present invention provides a method for automatically configuring a transmit/receive configuration of a device connector. The method includes detecting whether a link is present between first and second devices, switching a transmit/receive configuration of the first device from a first configuration to a second configuration if no link is detected, then periodically continuing to execute the steps of detecting and switching until detecting a link. Preferably, the time period of the transmit/receive configuration switching is at least as long as a minimum settle time to permit the associated components sufficient time to settle. To prevent a deadlock between two devices including auto configuration devices, the period length may be randomized.